RouterOS does support String comparison
There are few bugs in the script so maybe that is why it is not working.
Remember to put proper construction of :if statement. There are missing "do=" syntax. proper syntax is :if (sth) do={} else={}
delay command must be followed by ":" so :delay time_in_secs is proper syntax.
Once combining plain text with variable into 1 string put it inside brackets in the following manner: :log info ("test notification number: ".$variable);